Scientists Identify Critical Species from Gulf Oil Spill

A new study from a Coastal Waters Consortium team of researchers has found which birds,
fish, insects and other animals affected by the Deepwater Horizon explosion should
be given top priority for conservation, protection and research.

Until now scientists didn’t know which kinds of animals were most affected and what
impact their collective fates had on the food web after the offshore oil rig Deepwater
Horizon exploded in 2010 and dumped 4.9 million barrels of oil into Louisiana’s salt
marshes.

“There were lots of studies about who eats whom, and about what species are sensitive
to oil,” said Olaf Jensen, professor of marine and coastal sciences in the School
of Environmental and Biological Sciences at Rutgers University, and co-author of the
study. “We put those together and asked, ‘Who is both important in the food web and
really sensitive to oil?’” These are the species most in need of protection because
their loss can have ripple effects throughout the food web, Jensen said.

The study, published today in Frontiers in Ecology and the Environment, in which the
team of scientists from Rutgers University, LSU, Louisiana Universities Marine Consortium,
University of North Carolina, East Carolina University and Stony Brook University
constructed a marsh food web for Barataria Bay, La.

“The framework we built gives us a jump start on which keystone species to monitor
if and when another oil spill occurs, because changes in important and sensitive species
will have a ripple effect throughout the food web,” said co-author Michael Polito,
assistant professor of oceanography and coastal studies at LSU College of the Coast
& Environment.

The study found that killifish played a key role in the food web and fared relatively
well in the wake of the spill. The researchers also determined that terns, gulls and
wading birds, such as herons, were both sensitive to oil and so extensively connected
to other animals as prey and predator that their loss would impact other species in
the food web. Some studies indicate that the mortality among terns and gulls in Barataria
Bay was as high as 32 percent.

“We didn’t just want to find winners and losers from the effects of the spill,” said
Mike McCann, the study’s lead author, now a scientist at the Nature Conservancy but
a Rutgers postdoctoral researcher when the study was done. “We wanted to find out
what role each kind of animal would play in how a food web responds to something like
this oil spill.”

Some animals, such as roundworms, were found to be highly sensitive to the oil, but
were not considered to be critical to the food web because they are not highly connected
to other animals as prey or predator.

Finally, the scientists identified several animals as key to the saltmarsh ecosystem
that should be considered top priorities for future research. Blue crabs were among
such animals.

“Our analysis identified blue crab as one of the most important species in the Louisiana
salt marshes because they eat or are eaten by nearly every other animal in this environment,”
Polito said. “As the sensitivity of blue crabs to oil is still unclear, future work
is needed to clarify how oil spills might affect this important species and result
in changes throughout the salt marsh ecosystem.”

This collaborative Coastal Waters Consortium effort was made possible by a grant from
the Gulf of Mexico Research Initiative, or GoMRI.